The present invention relates to a foot-operated control device with a regulating unit, an installed cable drum and a reset spring for electrically driven appliances. More particularly, the present invention is directed to a foot-operated control device which is used with household appliances, e.g., sewing machines.
In conventional control devices of this type, current is transmitted via relatively movable parts, for example carbon brushes, wiper contacts, etc., which leads to the wear and tear of various elements due to sparking caused by poor transmitting conditions produced by soiling or oxidation. Since in such control devices a reset spring is customarily provided which effects the retraction of the pulled-out cable, a blocking means must be included which fixes the cable to the pulled-out length. In the control devices known heretofore, these blocking means are, in most cases, comprised of clamping-type safety catches which can be triggered by manual or remote operation. Since these clamping-type safety catches are not released by positive switchover control by the cable drum proper, additional manipulations are required which lead to a cumbersome operation, especially in the present instance where foot-operated devices are involved.
In case of foot-operated control devices forming accessories to a household appliance, the structural size is frequently limited because of space limitations. Furthermore, the installation of a cable drum into such appliances causes some difficulties for the reasons that it is difficult to provide a suitable arrangement of the drum and the regulator unit, especially in control devices containing a treadle pivotable about an axis essentially disposed underneath the ankle joint, since only the space lying in front of the axis is available and can be utilized for the installation of the cable drum and the regulator unit.
Accordingly, an object of the present invention is to provide a control device of the type mentioned hereinabove wherein, by the avoidance of relatively movable current-transmitting elements, a flawless current passage is ensured without producing undesirable wear and wherein the control device makes it possible to effect a space-saving, compact construction and simple manipulation.
Further scope of applicability of the present invention will become apparent from the detailed description given hereinafter. However, it should be understood that the detailed description and specific examples, while indicating preferred embodiments of the invention, are given by way of illustration only, since various changes and modifications within the spirit and scope of the invention will become apparent to those skilled in the art from this detailed description.
The control device of the present invention comprises a housing with a receiving chamber for the cable drum which is rotatable about a fixed axis, a regulator member of a potentiometer fixedly installed in the hub portion of the cable drum, and a treadle supported outside of the chamber at the housing, said treadle carrying a slide, which is connected to the treadle in an articulated and rotatable fashion, is vertically guided in the drum, and is provided with the tap contacts of the potentiometer, said slide being fixedly connected with the regulator member in a nonrotational manner.
Because of this type of construction, there is no relative movement between the tap elements and the regulator member of the potentiometer fixedly joined to the cable drum, during the extraction or retraction of the cable causing the revolving of the cable drum. The treadle movement is transmitted via the tappet to the vertically movable slide. The treadle, which is suitably fashioned as a housing lid, is advantageously supported at the housing by two axle stubs leaving between them a free housing space located beside the cable drum. The blocking means for the cable, activatable by remote control and cooperating with the periphery of the cable drum, is disposed in this free housing space. This permits an especially compact construction of the device.